A torque measuring device for a rotating body is set between a driving shaft powered and a driven shaft loaded, and measures a rotating torque in a non-contact manner. Such a torque measuring device is disclosed in, for example, Japanese Patent Application Laid-Open No. 2002-22566, which is used, for example, to measure a rotating torque between a measurement roller and a brake system in a chassis dynamo rotated by a wheel of a vehicle.
In Japanese Patent Appln. Laid-Open No. 2002-22566, FIG. 1 is a front view of a conventional torque measuring device 50 for a rotating body, and FIG. 2 is a side view (partly cut away and sectioned) of the conventional torque measuring device 50 of FIG. 1. As shown in FIGS. 1 and 2, the conventional torque measuring device 50 comprises: a rotary section 51 rotatably disposed between a driving shaft 91 powered and a driven shaft 93 loaded; and a stationary section 55 fixedly disposed so as to surround the rotary section 51. The rotary section 51 integrally comprises: a first flange 52 to be fixedly jointed to a driving shaft flange 92 of the driving shaft 91; a second flange 54 to be fixedly jointed to a driven shaft flange 94 of the driven shaft 93; and a hollow cylinder 53 having a hollow 59, and having the first and second flanges 52 and 54 formed respectively on both edges thereof. The stationary section 55 comprises: an annulus 56 located so as to surround the second flange 54; and a chassis 57 to which the annulus 56 is fixedly attached via attaching members 58.
A primary coil 87 is provided at the inner circumference of the annulus 56 disposed outside the second flange 54, and a secondary coil 88 is provided at the outer circumference of the second flange 54. The primary and secondary coils 87 and 88 in combination constitute a rotary transformer 89, thereby supplying electric power to the rotary section 51.
Torque detectors 61 as strain gauges are provided at the inner circumference of the hollow cylinder 53, a plurality of light emitting elements 67a to 67n, which are adapted to emit light according to an output from the torque detectors 61 thereby outputting an optical signal, are provided at the outer circumference of the second flange 54 so as to be arrayed along the secondary coil 88, a light receiving fiber 71 for receiving the optical signal from the light emitting elements 67a to 67n is provided along the primary coil 87 on the inner circumference of the annulus 56, and optical-electrical signal converters (not shown) for converting the optical signal into an electrical signal are provided at the ends of the light receiving fiber 71.
In the torque measuring device 50, when the driving shaft 91 rotates, the output from the torque detectors 61 is carried via the light emitting elements 67a to 67n and the light receiving fiber 71 to the optical-electrical signal converters (not shown) and is thereby detected, thus measuring a rotating torque.
As described above, the torque measuring device 50 for a rotating body is set between the driving shaft 91 and the driven shaft 93 and is capable of measuring a rotating torque in a non-contact manner. In such a torque measuring system, if the light receiving fiber 71 to receive the output from light emitting elements 67a to 67n is scratched or damaged, the optical signal carried therethrough may possibly be impaired, and therefore the light receiving fiber 71 must be carefully fitted in the groove at the annulus 56 thus ever seeking improvement of workability in fitting the optical components.
And, since the light receiving fiber 71 which is disposed in a circle is adapted to receive the optical signal from the light emitting elements 67a to 67n from the center of the circle, and since the light receiving fiber 71 is adapted to transmit the received optical signal therethrough in a circular way, the optical signal received is not smoothly transmitted, and therefore improvement of efficiency in receiving the optical signal is also sought.
Under the circumstances described above, an invention to address the improvements sought was made by the present applicant under Japanese Patent Application No. 2003-90334.
The present invention is provided to solve the problems discussed above and other problems, and to provide advantages and aspects not provided by prior invention of this type. A full discussion of the features and advantages of the present invention is deferred to the following detailed description, which proceeds with reference to the accompanying drawings.